Android: Make BACK button show HOME button behaviour

On Android, the HOME button does by default suspend the application, i.e. bring it into background so that the user can continue his game from where he left off when he comes back.

It’s also fairly easy to make the game quit when clicking the BACK button.

However, what I want to achieve is that the BACK button should show the same behaviour as does the HOME button, i.e. to suspend the application into background.

So:

void Update()
{
	if (Input.GetKeyDown(KeyCode.Escape))
	{
		// What should I do here?
	}
}